Freedom of movement across the European Union should be protected with improved cross-border criminal record checks, Catherine Bearder MEP has said.
It comes as Jonathan Limani was jailed for life after killing his boss Christopher Varian with a cheese knife in an act described by a judge as the "ultimate in violence".
Limani, 34, admitted manslaughter on the grounds of diminished responsibility at Oxford Crown Court on Monday and was sent to Broadmoor Hospital.
Catherine has now called on the European Commission to explain what checks are in place to ensure employers know the background of people they employ from other EU countries.
Limani, who had a history of mental ill health and a conviction for drug dealing, had only been in the UK for two weeks before beheading Christopher Varian.
Mr Varian's family believed a catalogue of errors led to Limani being able to live and work in the UK at the Oxfordshire Golf Club in Thame.
Limani had a conviction for supplying heroin in Switzerland and moved to Britain from Sweden where he had been sectioned for being mentally ill.
Catherine said: "Mr Varian's family has endured a torrid two years and will take little comfort from Monday's sentence.
"Limani had a conviction in a non-European Union country, but was able to cut free from his criminal past by moving into the EU.
"Freedom of movement and ability to work is a cornerstone of what the EU stands for, but the safety of its citizens is of paramount importance."
Catherine has asked the European Commission to explain what checks are in place on the criminal backgrounds of people working in the EU.
She has also called on the commission to investigate the potential for cross-border employment agencies to carry out criminal record checks on employees.
Catherine added: "This is about improving cooperation with our EU neighbours to prevent crimes like this from happening again."
Catherine has asked the European Commission the following questions:
- - What checks already in place were missed by the employment agency in Sweden that allowed Jonathan Limani to enter the UK to work freely?
- - Does the Commission have any plans to investigate the implementation of a check on the criminal background of those entering and moving around the EU to live and work?
- - Does the Commission have any plans to investigate allowing cross-border employment agencies to conduct criminal record checks on prospective employees to prevent crimes like this happening again?